The aforementioned Patent and Patent Application disclose and claim a pumping system in which a quantity of pressurized product is stored in a storage compartment during a pressurizing stroke and discharged through an outlet orifice during a succeeding intake stroke to maintain a stream or spray issuing from the system. The present invention is directed to a special arrangement for a spring of the storage piston and cylinder device which is especially advantageous for keeping the stream or spray relatively steady. The pumping system of the type disclosed in the Patent and Patent Application identified above may also include a novel vent structure and a novel strainer arrangement in accordance with this invention.